Objective
The principal purposes of the project are the determinination of the crust formation ages within the main tectonic terrains of the Central Asian Mobile Belt (CAMB) and the determinination of the isotopic structure of the continental crust in the region in order to improve the understanding of the mechanisms and timing of crust formation, evolution and growth rates.
Understanding how and when continental crust was formed is of fundamental importance for thermal, chemical and tectonic models of global evolution. During the past few years, isotopic investigations have been used extensively to constrain possible models of continental crust formation and evolution through time, but many aspects of the history of continental crust development remain, however, a subject of considerable controversy and international discussion. The current research will determine, among others, what proportion of the crust is juvenile and what proportion consists of reworked, older material. It will also be found out whether the CAMB is a tectonic collage of island arcs and microcontinents, as presently observed in the Indonesian region of SE Asia, or whether it consists of largely continuous basement blocks that are separated by narrow "oceanic" terrains.
A combination of whole rock major and trace element geochemistry together with Sm-Nd whole rock and U-Pb and Pb-Pb zircon systematics will be used to determine the petrogenesis, tectonic setting and geochronology of the felsic magmatic rocks. Particular emphasis will be placed on establishing a high precision low-blank isotope laboratory at one of the Russian participants and to transfer the most modern technology to them. Investigations will be performed on high-precision zircon ages with errors less than 0.5 %. All aspects of the whole rock geochemistry and the isotopic studies will be performed. Geochemical, isotopic and field data will be used to constrain models of crustal growth and evolution of the CAMB.
The data derived from this project are expected to lead to a better understanding of the tectonic evolution of the Central Asian Mobile Belt (CAMB) in the early Palaeozoic. In particular, it is expected to be able to recognise "oceanic" and "continental" terrains, whether oceanic basins between these terrains were large or small, and whether the currently suspected microcontinents were derived from Gondwanaland or constitute detached fragments of the Siberian Shield. Another result of this project will the possibility to confirm or disprove the model whereby most of central Asia is supposed to represent juvenile material added to the crust during the early Palaeozoic.
Call for proposal
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55099 Mainz
Germany